| With the rapid development of economy, the use of energy is more and more widely. At thesame time, there is a growing emphasis on energy conservation. According to statistics,building energy consumption accounts for about a third of the total energy consumption, andAir-conditioning system energy consumption accounts for about40%~54%of the buildingenergy consumption. Building energy efficiency become the focus of energy conservationduring the twelfth five-year plan in China.Optimized control strategies were proposed on the basis of the detailed data analysis. Onthe purpose of optimizing the use time of unit, group control strategy was put forward.Variable water volume control strategy which used the terminal temperature differencecontrol method was put forward. In this paper the proposed optimization control methodabandoned single parameter control method and was Multi-parameter control method. Inorder to avoid the controlled environment temperature and humidity produce largerfluctuation which are caused by single-parameter control, end important units valve openingdegree and the end ambient temperature was added to the control parameter; on the purpose ofthe sum of Pump energy consumption and chiller energy consumption was least, variablewater temperature control strategy which improved the cooler cop by changing the frozenwater outlet temperature was put forward. Best cooler water temperature calculation formulawas put forward which was also based on the sum of Pump energy consumption and chillerenergy consumption was least. Parameters which were used in the formula included thedesign parameters of the chillers and pumps, current load, pump power, terminal ambienttemperature, terminal ambient humidity, etc. In order to minimize the sum of Chiller energyconsumption and pump energy consumption, variable water temperature and variable flowcontrol strategy operate at the same time. The proposed optimization strategy played a verygood control effect and energy saving effect.3The control strategy in the paper was used for the control of the air-conditioning system ofa drug safety testing laboratories. The system is fresh clean air conditioning and it has thecharacteristic of large load. The controlled environment is an international standard laboratorytemperature. The air conditioning system load data of the entire refrigeration season in2007is analyzed. The load rate is divided into five proportional band according to the rate of lessthan50%,50%~60%,60%~70%,70%~80%, higher than80%. Statistics data shows thatthe load rate is less than50%in most of the time and there exists a serious energy waste. Thecooling water temperature difference and chilled water temperature difference of the entire refrigeration season in2007are analyzed. The temperature difference is divided into fiveproportional band according to the difference of less than3degrees Celsius,3degreesCelsius~4degrees Celsius,4degrees Celsius~5degrees Celsius, higher than5degreesCelsius. Statistics data shows that the proportion of chilled water temperature differencewhich is less than3degrees is greater than69%and the proportion of cooling watertemperature difference which is less than3degrees is greater than87%. And because waterpump is fixed frequency pump, so the system wastes a lot of useless power. Through theanalysis of the original system diagnosis found that the original system operates in low loadcondition and exist serious flow small temperature difference phenomenon.All the control strategy implemented in the system is under the premise of safetyoperation, so the security of the system operation is the most basic guarantee. The systemsafety analysis mainly includes the analysis of the chilled water temperature range andanalysis of the chilled water pump frequency conversion range. The data of system chilledwater outlet temperature and freezing pump operation frequency which are collected beforethe operation optimization control were summarized, and chilled water temperature range ofsafe operation and pump frequency range were sorted out in the history of the chilled watertemperature and pump operating frequency data; The accuracy of the range was tested duringthe commissioning process. The safety range of the chilled water temperature and the freezingpump frequency is confirmed after three ways of common correction. In order to ensure thesafe operation of the system, the alarm settings were joined and alarm point was set for morethan one control point (such as ambient temperature, humidity, etc.). System will carry on thealarm if the value of the control point exceeds the safe range, and the staff can handle in time.The energy savings were calculated and the energy savings were expressed by the powerconsumption. The electricity data after transformation was real-time monitored by the dataacquisition system, and the electricity data before transformation was calculated by themathematical model that whose parameter includes meteorological correction parameters.After detailed statistics on energy savings data in2012, we can safely draw the conclusionthat pumps in energy saving is about63%, and cooler energy saving is about6%. |
